xref: /petsc/src/mat/impls/aij/seq/matptap.c (revision df4be7eeb7111d94d8a5a571d7e69f9c5048ca1d)
1 
2 /*
3   Defines projective product routines where A is a SeqAIJ matrix
4           C = P^T * A * P
5 */
6 
7 #include <../src/mat/impls/aij/seq/aij.h>   /*I "petscmat.h" I*/
8 #include <../src/mat/utils/freespace.h>
9 #include <petscbt.h>
10 #include <petsctime.h>
11 
12 #if defined(PETSC_HAVE_HYPRE)
13 PETSC_INTERN PetscErrorCode MatPtAPSymbolic_AIJ_AIJ_wHYPRE(Mat,Mat,PetscReal,Mat*);
14 #endif
15 
16 PETSC_INTERN PetscErrorCode MatPtAP_SeqAIJ_SeqAIJ(Mat A,Mat P,MatReuse scall,PetscReal fill,Mat *C)
17 {
18   PetscErrorCode      ierr;
19 #if !defined(PETSC_HAVE_HYPRE)
20   const char          *algTypes[2] = {"scalable","rap"};
21   PetscInt            nalg = 2;
22 #else
23   const char          *algTypes[3] = {"scalable","rap","hypre"};
24   PetscInt            nalg = 3;
25 #endif
26   PetscInt            alg = 1; /* set default algorithm */
27   Mat                 Pt;
28   Mat_MatTransMatMult *atb;
29   Mat_SeqAIJ          *c;
30 
31   PetscFunctionBegin;
32   if (scall == MAT_INITIAL_MATRIX) {
33     /*
34      Alg 'scalable' determines which implementations to be used:
35        "rap":      Pt = P^T and C = Pt*A*P
36        "scalable": do outer product and two sparse axpy in MatPtAPNumeric() - might slow, does not store structure of A*P.
37        "hypre":    use boomerAMGBuildCoarseOperator.
38      */
39     ierr = PetscObjectOptionsBegin((PetscObject)A);CHKERRQ(ierr);
40     PetscOptionsObject->alreadyprinted = PETSC_FALSE; /* a hack to ensure the option shows in '-help' */
41     ierr = PetscOptionsEList("-matptap_via","Algorithmic approach","MatPtAP",algTypes,nalg,algTypes[0],&alg,NULL);CHKERRQ(ierr);
42     ierr = PetscOptionsEnd();CHKERRQ(ierr);
43     switch (alg) {
44     case 1:
45       ierr = PetscNew(&atb);CHKERRQ(ierr);
46       ierr = MatTranspose_SeqAIJ(P,MAT_INITIAL_MATRIX,&Pt);CHKERRQ(ierr);
47       ierr = MatMatMatMult(Pt,A,P,MAT_INITIAL_MATRIX,fill,C);CHKERRQ(ierr);
48 
49       c                      = (Mat_SeqAIJ*)(*C)->data;
50       c->atb                 = atb;
51       atb->At                = Pt;
52       atb->destroy           = (*C)->ops->destroy;
53       (*C)->ops->destroy     = MatDestroy_SeqAIJ_MatTransMatMult;
54       (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ;
55       PetscFunctionReturn(0);
56       break;
57 #if defined(PETSC_HAVE_HYPRE)
58     case 2:
59       ierr = PetscLogEventBegin(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
60       ierr = MatPtAPSymbolic_AIJ_AIJ_wHYPRE(A,P,fill,C);CHKERRQ(ierr);
61       ierr = PetscLogEventEnd(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
62       break;
63 #endif
64     default:
65       ierr = PetscLogEventBegin(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
66       ierr = MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(A,P,fill,C);CHKERRQ(ierr);
67       ierr = PetscLogEventEnd(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
68       break;
69     }
70   }
71   ierr = PetscLogEventBegin(MAT_PtAPNumeric,A,P,0,0);CHKERRQ(ierr);
72   ierr = (*(*C)->ops->ptapnumeric)(A,P,*C);CHKERRQ(ierr);
73   ierr = PetscLogEventEnd(MAT_PtAPNumeric,A,P,0,0);CHKERRQ(ierr);
74   PetscFunctionReturn(0);
75 }
76 
77 PetscErrorCode MatDestroy_SeqAIJ_PtAP(Mat A)
78 {
79   PetscErrorCode ierr;
80   Mat_SeqAIJ     *a    = (Mat_SeqAIJ*)A->data;
81   Mat_PtAP       *ptap = a->ptap;
82 
83   PetscFunctionBegin;
84   ierr = PetscFree(ptap->apa);CHKERRQ(ierr);
85   ierr = PetscFree(ptap->api);CHKERRQ(ierr);
86   ierr = PetscFree(ptap->apj);CHKERRQ(ierr);
87   ierr = (ptap->destroy)(A);CHKERRQ(ierr);
88   ierr = PetscFree(ptap);CHKERRQ(ierr);
89   PetscFunctionReturn(0);
90 }
91 
92 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,PetscReal fill,Mat *C)
93 {
94   PetscErrorCode     ierr;
95   PetscFreeSpaceList free_space=NULL,current_space=NULL;
96   Mat_SeqAIJ         *a        = (Mat_SeqAIJ*)A->data,*p = (Mat_SeqAIJ*)P->data,*c;
97   PetscInt           *pti,*ptj,*ptJ,*ai=a->i,*aj=a->j,*ajj,*pi=p->i,*pj=p->j,*pjj;
98   PetscInt           *ci,*cj,*ptadenserow,*ptasparserow,*ptaj,nspacedouble=0;
99   PetscInt           an=A->cmap->N,am=A->rmap->N,pn=P->cmap->N,pm=P->rmap->N;
100   PetscInt           i,j,k,ptnzi,arow,anzj,ptanzi,prow,pnzj,cnzi,nlnk,*lnk;
101   MatScalar          *ca;
102   PetscBT            lnkbt;
103   PetscReal          afill;
104 
105   PetscFunctionBegin;
106   /* Get ij structure of P^T */
107   ierr = MatGetSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
108   ptJ  = ptj;
109 
110   /* Allocate ci array, arrays for fill computation and */
111   /* free space for accumulating nonzero column info */
112   ierr  = PetscMalloc1(pn+1,&ci);CHKERRQ(ierr);
113   ci[0] = 0;
114 
115   ierr         = PetscCalloc1(2*an+1,&ptadenserow);CHKERRQ(ierr);
116   ptasparserow = ptadenserow  + an;
117 
118   /* create and initialize a linked list */
119   nlnk = pn+1;
120   ierr = PetscLLCreate(pn,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
121 
122   /* Set initial free space to be fill*(nnz(A)+ nnz(P)) */
123   ierr          = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,PetscIntSumTruncate(ai[am],pi[pm])),&free_space);CHKERRQ(ierr);
124   current_space = free_space;
125 
126   /* Determine symbolic info for each row of C: */
127   for (i=0; i<pn; i++) {
128     ptnzi  = pti[i+1] - pti[i];
129     ptanzi = 0;
130     /* Determine symbolic row of PtA: */
131     for (j=0; j<ptnzi; j++) {
132       arow = *ptJ++;
133       anzj = ai[arow+1] - ai[arow];
134       ajj  = aj + ai[arow];
135       for (k=0; k<anzj; k++) {
136         if (!ptadenserow[ajj[k]]) {
137           ptadenserow[ajj[k]]    = -1;
138           ptasparserow[ptanzi++] = ajj[k];
139         }
140       }
141     }
142     /* Using symbolic info for row of PtA, determine symbolic info for row of C: */
143     ptaj = ptasparserow;
144     cnzi = 0;
145     for (j=0; j<ptanzi; j++) {
146       prow = *ptaj++;
147       pnzj = pi[prow+1] - pi[prow];
148       pjj  = pj + pi[prow];
149       /* add non-zero cols of P into the sorted linked list lnk */
150       ierr  = PetscLLAddSorted(pnzj,pjj,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
151       cnzi += nlnk;
152     }
153 
154     /* If free space is not available, make more free space */
155     /* Double the amount of total space in the list */
156     if (current_space->local_remaining<cnzi) {
157       ierr = PetscFreeSpaceGet(PetscIntSumTruncate(cnzi,current_space->total_array_size),&current_space);CHKERRQ(ierr);
158       nspacedouble++;
159     }
160 
161     /* Copy data into free space, and zero out denserows */
162     ierr = PetscLLClean(pn,pn,cnzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
163 
164     current_space->array           += cnzi;
165     current_space->local_used      += cnzi;
166     current_space->local_remaining -= cnzi;
167 
168     for (j=0; j<ptanzi; j++) ptadenserow[ptasparserow[j]] = 0;
169 
170     /* Aside: Perhaps we should save the pta info for the numerical factorization. */
171     /*        For now, we will recompute what is needed. */
172     ci[i+1] = ci[i] + cnzi;
173   }
174   /* nnz is now stored in ci[ptm], column indices are in the list of free space */
175   /* Allocate space for cj, initialize cj, and */
176   /* destroy list of free space and other temporary array(s) */
177   ierr = PetscMalloc1(ci[pn]+1,&cj);CHKERRQ(ierr);
178   ierr = PetscFreeSpaceContiguous(&free_space,cj);CHKERRQ(ierr);
179   ierr = PetscFree(ptadenserow);CHKERRQ(ierr);
180   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
181 
182   ierr = PetscCalloc1(ci[pn]+1,&ca);CHKERRQ(ierr);
183 
184   /* put together the new matrix */
185   ierr = MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A),pn,pn,ci,cj,ca,C);CHKERRQ(ierr);
186   ierr = MatSetBlockSizes(*C,PetscAbs(P->cmap->bs),PetscAbs(P->cmap->bs));CHKERRQ(ierr);
187 
188   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
189   /* Since these are PETSc arrays, change flags to free them as necessary. */
190   c          = (Mat_SeqAIJ*)((*C)->data);
191   c->free_a  = PETSC_TRUE;
192   c->free_ij = PETSC_TRUE;
193   c->nonew   = 0;
194   (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy;
195 
196   /* set MatInfo */
197   afill = (PetscReal)ci[pn]/(ai[am]+pi[pm] + 1.e-5);
198   if (afill < 1.0) afill = 1.0;
199   c->maxnz                     = ci[pn];
200   c->nz                        = ci[pn];
201   (*C)->info.mallocs           = nspacedouble;
202   (*C)->info.fill_ratio_given  = fill;
203   (*C)->info.fill_ratio_needed = afill;
204 
205   /* Clean up. */
206   ierr = MatRestoreSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
207 #if defined(PETSC_USE_INFO)
208   if (ci[pn] != 0) {
209     ierr = PetscInfo3((*C),"Reallocs %D; Fill ratio: given %g needed %g.\n",nspacedouble,(double)fill,(double)afill);CHKERRQ(ierr);
210     ierr = PetscInfo1((*C),"Use MatPtAP(A,P,MatReuse,%g,&C) for best performance.\n",(double)afill);CHKERRQ(ierr);
211   } else {
212     ierr = PetscInfo((*C),"Empty matrix product\n");CHKERRQ(ierr);
213   }
214 #endif
215   PetscFunctionReturn(0);
216 }
217 
218 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,Mat C)
219 {
220   PetscErrorCode ierr;
221   Mat_SeqAIJ     *a = (Mat_SeqAIJ*) A->data;
222   Mat_SeqAIJ     *p = (Mat_SeqAIJ*) P->data;
223   Mat_SeqAIJ     *c = (Mat_SeqAIJ*) C->data;
224   PetscInt       *ai=a->i,*aj=a->j,*apj,*apjdense,*pi=p->i,*pj=p->j,*pJ=p->j,*pjj;
225   PetscInt       *ci=c->i,*cj=c->j,*cjj;
226   PetscInt       am =A->rmap->N,cn=C->cmap->N,cm=C->rmap->N;
227   PetscInt       i,j,k,anzi,pnzi,apnzj,nextap,pnzj,prow,crow;
228   MatScalar      *aa=a->a,*apa,*pa=p->a,*pA=p->a,*paj,*ca=c->a,*caj;
229 
230   PetscFunctionBegin;
231   /* Allocate temporary array for storage of one row of A*P (cn: non-scalable) */
232   ierr = PetscMalloc3(cn,&apa,cn,&apjdense,cn,&apj);CHKERRQ(ierr);
233   ierr = PetscMemzero(apa,cn*sizeof(MatScalar));CHKERRQ(ierr);
234   ierr = PetscMemzero(apjdense,cn*sizeof(PetscInt));CHKERRQ(ierr);
235 
236   /* Clear old values in C */
237   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
238 
239   for (i=0; i<am; i++) {
240     /* Form sparse row of A*P */
241     anzi  = ai[i+1] - ai[i];
242     apnzj = 0;
243     for (j=0; j<anzi; j++) {
244       prow = *aj++;
245       pnzj = pi[prow+1] - pi[prow];
246       pjj  = pj + pi[prow];
247       paj  = pa + pi[prow];
248       for (k=0; k<pnzj; k++) {
249         if (!apjdense[pjj[k]]) {
250           apjdense[pjj[k]] = -1;
251           apj[apnzj++]     = pjj[k];
252         }
253         apa[pjj[k]] += (*aa)*paj[k];
254       }
255       ierr = PetscLogFlops(2.0*pnzj);CHKERRQ(ierr);
256       aa++;
257     }
258 
259     /* Sort the j index array for quick sparse axpy. */
260     /* Note: a array does not need sorting as it is in dense storage locations. */
261     ierr = PetscSortInt(apnzj,apj);CHKERRQ(ierr);
262 
263     /* Compute P^T*A*P using outer product (P^T)[:,j]*(A*P)[j,:]. */
264     pnzi = pi[i+1] - pi[i];
265     for (j=0; j<pnzi; j++) {
266       nextap = 0;
267       crow   = *pJ++;
268       cjj    = cj + ci[crow];
269       caj    = ca + ci[crow];
270       /* Perform sparse axpy operation.  Note cjj includes apj. */
271       for (k=0; nextap<apnzj; k++) {
272 #if defined(PETSC_USE_DEBUG)
273         if (k >= ci[crow+1] - ci[crow]) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"k too large k %d, crow %d",k,crow);
274 #endif
275         if (cjj[k]==apj[nextap]) {
276           caj[k] += (*pA)*apa[apj[nextap++]];
277         }
278       }
279       ierr = PetscLogFlops(2.0*apnzj);CHKERRQ(ierr);
280       pA++;
281     }
282 
283     /* Zero the current row info for A*P */
284     for (j=0; j<apnzj; j++) {
285       apa[apj[j]]      = 0.;
286       apjdense[apj[j]] = 0;
287     }
288   }
289 
290   /* Assemble the final matrix and clean up */
291   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
292   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
293 
294   ierr = PetscFree3(apa,apjdense,apj);CHKERRQ(ierr);
295   PetscFunctionReturn(0);
296 }
297 
298 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ(Mat A,Mat P,Mat C)
299 {
300   PetscErrorCode      ierr;
301   Mat_SeqAIJ          *c = (Mat_SeqAIJ*)C->data;
302   Mat_MatTransMatMult *atb = c->atb;
303   Mat                 Pt = atb->At;
304 
305   PetscFunctionBegin;
306   ierr = MatTranspose_SeqAIJ(P,MAT_REUSE_MATRIX,&Pt);CHKERRQ(ierr);
307   ierr = (C->ops->matmatmultnumeric)(Pt,A,P,C);CHKERRQ(ierr);
308   PetscFunctionReturn(0);
309 }
310